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NASA-Funded Scientists Make Lunar Watershed Discovery



MOFFETT FIELD, Calif. -- A team of NASA-funded researchers has
measured for the first time water from the moon in the form of tiny
globules of molten rock, which have turned to glass-like material
trapped within crystals. Data from these newly-discovered lunar melt
inclusions indicate the water content of lunar magma is 100 times
higher than previous studies suggested.

The inclusions were found in lunar sample 74220, the famous
high-titanium "orange glass soil" of volcanic origin collected during
the Apollo 17 mission in 1972. The scientific team used a
state-of-the-art ion microprobe instrument to measure the water
content of the inclusions, which were formed during explosive
eruptions on the moon approximately 3.7 billion years ago.

The results published in the May 26 issue of Science Express raise
questions about aspects of the "giant impact theory" of how the moon
was created. That theory predicted very low water content of lunar
rock due to catastrophic degassing during the collision of Earth with
a Mars-sized body very early in its history.

The study also provides additional scientific justification for
returning similar samples from other planetary bodies in the solar system.

"Water plays a critical role in determining the tectonic behavior of
planetary surfaces, the melting point of planetary interiors and the
location and eruptive style of planetary volcanoes," said Erik Hauri,
a geochemist with the Carnegie Institution of Washington and lead
author of the study. "I can conceive of no sample type that would be
more important to return to Earth than these volcanic glass samples
ejected by explosive volcanism, which have been mapped not only on
the moon but throughout the inner solar system."

In contrast to most volcanic deposits, the lunar melt inclusions are
encased in crystals that prevent the escape of water and other
volatiles during eruption.

"These samples provide the best window we have on the amount of water
in the interior of the moon where the orange glass came from," said
science team member James Van Orman of Case Western Reserve
University in Cleveland.

In a 2008 study led by Alberto Saal of Brown University in Providence,
R.I., the same team reported the first evidence of water in lunar
volcanic glasses. They used magma degassing models to estimate how
much water was originally in the magmas before eruption.
Building on that study, a Brown undergraduate student, Thomas
Weinreich, searched for and found the melt inclusions. With that
data, the team measured the pre-eruption concentration in the magma
and estimated the amount of water in the moon's interior.

"The bottom line is that in 2008, we said the primitive water content
in the lunar magmas should be similar to lavas coming from the
Earth's depleted upper mantle," Saal said. "Now, we have proven that
is indeed the case."

The study also puts a new twist on the origin of water-ice detected in
craters at the lunar poles by several recent NASA missions. The ice
has been attributed to comet and meteor impacts, but the researchers
believe it is possible that some of the ice came from water released
by the eruption of lunar magmas eons ago.

The paper entitled, "High Pre-Eruptive Water Contents Preserved in
Lunar Melt Inclusions," was written by Hauri, Weinreich, Saal, Van
Oman and Malcolm Rutherford of Brown. The research is funded by
NASA's Lunar Advanced Science and Exploration Research and
Cosmochemistry Programs in Washington, the NASA Lunar Science
Institute (NLSI) at the agency's Ames Research Center at Moffett
Field, Calif., and the Astrobiology Institute at Ames.

The NLSI is a virtual organization enabling collaborative,
interdisciplinary research in support of agency lunar science
programs. The researchers are members of NLSI teams from the
Southwest Research Institute in San Antonio and Brown. The institute
uses technology to bring scientists together around the world, and it
is comprised of seven competitively selected U.S. teams and several
international partners. NASA's Science Mission and Exploration
Systems Mission Directorates in Washington fund the institute.

For more information about the NLSI, visit:

http://lunarscience.nasa.gov

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